The Kidde Carbon Monoxide Detector, Battery Powered CO Alarm with LEDs, Test- Reset Button, Low Battery Indicator, Portable, model 9CO5LP2, is a carbon monoxide detector that uses electrochemical sensor technology to detect carbon monoxide. The CO detector is powered by 2-AA alkaline batteries located in the back of the unit, providing easy installation & no wiring, plus coverage during a power failure. The alarm is conveniently designed and portable enough for travel - simply install it on a wall or place it on a tabletop. When carbon monoxide is detected, an 85-decibel alarm will sound & a red LED will flash. A green LED indicates that the alarm is receiving power. The test-hush button allows you to test the battery operations as well as temporarily silence the low battery chirp warning. Install a smoke detector & carbon monoxide detector on every level of your home and near bedrooms to help keep your family safe from fire & poisonous gas. UL Certified with a 10-year limited manufacturer's warranty.